Photographic compositions containing bis-isothiuronium compounds as development activators and image stabilizers

ABSTRACT

CERTAIN BIS-ISOTHIURONIUM COMPOUNDS HAVING AN INTERMEDIATE UREYLENE OR ETHER MOIETY PROVIDE ACTIVATION OF A SILVER HALIDE DEVELOPING AGENT UPON HEATING IN THE ABSENCE OF A SEPARATE DEVELOPMENT ACTIVATOR. A PHOTOGRAPHIC ELEMENT OR COMPOSITION CONTAINING THE BIS-ISOTHIURONIUM COMPOUNDS AND A SILVER HALIDE DEVELOPING AGENT CAN CONTAIN OTHER ADDENDA SUITABLE IN PHOTOGRAPHIC ELEMEMTS AND/ OR COMPOSITIONS. THE DESCRIBED BIS-ISOTHIOURANIUM COMPOUNDS CAN ALSO PROVIDE STABILIZATION OF A RESULTING DEVELOPED IMAGE.

United States Patent 3,669 670 PHOTOGRAPHIC COMIOSITIONS CONTAIN- ING BIS-ISOTHIURONIUM COMPOUNDS AS DEVELOPMENT ACTIVATORS AND IMAGE STABILIZERS Grant M. Haist and Wilbert J. Humphlett, Rochester,

N.Y., assiguors to Eastman Kodak Company, Rochester, N.Y. No Drawing. Filed Dec. 2, 1970, Ser. No. 94,568 Int. Cl. G03c 1/06 U.S. Cl. 9695 14 Claims ABSTRACT OF THE DISCLOSURE Certain bis-isothiuronium compounds having an intermediate ureylene or ether moiety provide activation of a silver halide developing agent upon heating in the absence of a separate development activator. A photographic element or composition containing the bis-isothiuronium compounds and a silver halide developing agent can contain other addenda suitable in photographic elements and/ or compositions. The described bis-isothiouranium compounds can also provide stabilization of a resulting developed image.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to certain bis-isothiuronium compounds having an intermediate ureylene or ether moiety between the isothiouronium moieties and to their use in photographic elements, compositions and processes. In one aspect the invention relates to photographic elements containing the described bis-isothiuronium compounds. In another aspect it relates to photographic compositions, e.g. photographic silver halide emulsions, containing the described bis-isothiouronium compounds. A further aspect is a method of developing a latent image in a photographic element employing such bis-isothiuronium compounds by heating the element.

Description of the state of the art Photographic elements and compositions are known which are designed for processing with heat. These are described, for example, in U.S. Pat. 3,301,678 of Humphlett, Johnson and Haist, issued Jan. 31, 1967; Belgian Pat. 709,967; British Pat. 1,161,777; U.S. Pat. 3,152,904 of Sorensen et al., issued Oct. 13, 1964; British Pat. 1,131,- 108; U.S Pat. 3,391,020 of Yutzy and Yackel, issued July 9, 1968; German Pat. 888,045; and British Pat. 930,572; and U.S. 3,220,846 of Tinker and Sagura, issued Nov. 30, 1965.

Stabilizer precursors are also known in photographic elements for processing with heat. These are described for example in U.S. Pat. 3,301,678 of Humphlett, Johnson and Haist, issued Jan. 31, 1967. In such photographic elements it has been the practice to employ a development activator and/or alkali release agent which is different from the developing agent or developing agent precursor or stabilizer precursor. This is described in U.S. Pat. 3,041,170 of Haist and King, issued June 26, 1962 and Belgian Pat. 709,967. No photographic element up to this time has been proposed which employs a silver halide developing agent which is activated by alkali, e.g. a pH of about 8 to about 14, and which eliminates the need for this separate development activator and/or alkali release agent.

There accordingly has been a continuing need to provide a photographic element for processing with heat which contains one component which upon heating activates the developing agent present to provide desired development 3,669,670 Patented June 13, 1972 and, generates a stabilizer for the developed image at the desired time, without undesired inhibition of development before the desired image is developed as well as without other undesired sensitometric properties.

SUMMARY OF THE INVENTION According to the invention, the described properties are provided by employing a bis-isothiuronium compound, especially a stabilizer precursor and/or a development activator precursor, having an intermediate ureylene or ether moiety between the isothiuronium moieties of the hisisothiouronium compound in a photographic element, composition and/or process for developing a latent image with heat. The described bis-isothiuronium compound provides, upon heating, activation of a developing agent present and/or stabilization of a developed image, without undesired sensitometric properties.

DETAILED DESCRIPTION OF THE INVENTION A range of bis-isothiuronium compounds can be employed according to the invention. Suitable bis-isothiuronium compounds include compounds represented by the formula:

HzN NH; 5

wherein R R and R are each alkylene containing one to five carbon atoms, e.g. methylene, ethylene, propylene, 1,3-trimethylene, 1,4-tetramethylene, 1,5-pentamethylene; Y is sulfur, oxygen or ureylene, i.e.

n is 0, l or 2; when n is 0 and Y is oxygen or sulfur, R plus R contain at least two carbon atoms; X is an anion, e.g. chloride, bromide, p-toluenesulfonate, sulfonate, trifluoroacetate, acetate, chloroacetate, ethyl sulfate or formate, with p-toluenesul'fonate being preferred; m is 1 or 2. Examples of suitable bis-isothiuronium compounds are:

1,8-( 3,6-dioxaoctane)bis (isothiuronium trifiuoroacetate) 1,-8- 3,6-dioxaoctane bis (isothiouronium chloride) monohydrate 1,8-(3,6-dioxaoctane)bis (isothiuronium acetate) l,8-(3,6-dioxaoctane)bis (isothiuronium chloroacetate) 1,8- (3,6-dioxaoctane)bis(isothiuronium dichloroacetate) 1,8-(3,6-dioxaoctane)bis(isothiuronium formate) l,8-(3,6-dioxaoctane)bis (isothiuronium p-toluenesulfonate) 1,8-(3,6-dioxaoctane)bis (isothiuronium nitrate) 1,7-(4-oxaheptane)bis (isothiuronium chloride) dihydrate l,9-(oxanonane)bis(isothiuronium chloride) 1,12-bis(isothiuronium) -4,9-dioxo-3,5,8,10-tetraazadodecane dichloride 1,3-bis(2-isothiuroniurnethyl)urea bis(trifluoroacetate) 1 ,3 -bis (2-isothiuroniumethyl) urea bis (p-toluenesulfonate) N,N'-bis 2-isothiuroniumethyl) urea dichloride 1,8- 3,=6-dithiaoctane bis (isothiuronium chloride) 1,5 3-oxapentane bis isothiuronium chloride) dihydrate 1,3-(2-oxapropane)bis(isothiouronium chloride) 1,7- (4-oxaheptane bis (isothiuronium p-toluenesulfonate) Compounds within the scope of Formula I wherein Y is sulfur or oxygen, i.e. a bis-isothiuronium compound having an ether moiety intermediate between the isothiuronium moieties, can be prepared by reacting a corresponding chloroalkoxy alkane with thiourea in a suitable solvent, such as isop-ropanol or ethanol. The reactants are typically mixed in about stoichiometric concentrations and the reactant mixture in the solvent can be heated to reflux temperature, e.g. about 40 C. to about 80 C. until reaction completion. An excess of thiourea can be employed to provide improved yields of the desired product. The reaction is typically carried out at atmospheric pressure. The reaction product can be recovered, such as by filtration. The preparation of 1,8- (3,6-dioxaoctane)bis(isothiuronium chloride) monohydrate is representative of the preparation of these compounds. According to this method 1,2-bis(2-chloroethoxy) ethane is mixed with thiourea in isopropanol. The reactants are mixed in about stoichiometric concentrations and the resulting mixture is heated to reflux temperature until reaction completion. The product is recovered, e.g. by cooling the reaction mixture and separating the product by filtration. It can be purified by recrystallization from a suitable solvent, e.g. methanol or isopropanol.

Compounds within the scope of Formula I wherein Y is ureylene, i.e.

can be prepared by reacting the corresponding urea compound, e.g. N,N'-bis(chloroalkyl)urea or a bis-chloride compound represented by the formula:

wherein a is a whole number, e.g. 1 to 5, with thiourea in a suitable solvent, e.g. ethanol or methanol. These reactants are typically mixed in about stoichiometric concentrations. The resulting reactant mixture can be heated to reflux temperature, e.g. about 40 C. to about 80 C. until reaction completion. The reaction is typically carried out at atmospheric pressure and the reaction product can be recovered, such as by filtration. The preparation of 1,3-bis(isothiuroniumethyl)urea bis(trifiuoroacetate) is representative of this method of preparation. This compound is prepared by reacting N,N-bis(chloroethyl)urea with thiourea in a suitable solvent, e.g. ethanol. The reactants are mixed in the solvent in about stoichiometric concentrations and the resulting mixture heated to reflux temperature, e.g. about 80 C., until reaction completion. A small concentration of sulfolane can be mixed with the solvent which is. sufficient to provide the desired reflux temperature. The resulting chloride compound can be recovered, e.g. by filtration, and converted to the corresponding trifiuoroacetate compound by mixing the chloride compound with silver trifluoroacetate in a suitable solvent, e.g. isopropanol or methanol. The chloride compound and silver trifluoroacetate can be mixed in about stoichiometric concentrations.

The described his chloride compounds of Formula H can be prepared by reacting the corresponding chloroalkylisocyanate with a diamine of the formula:

wherein a is a whole number, e.g. 1 to 5. This reaction can be carried out by mixing the reactants in about stoichiometric concentrations in a solvent which does not adversely affect the reaction, e.g. in chloroform or methylene chloride, and heating the resulting reactant mixture at reflux temperature, e.g. about 40 C. to about 80 C., until reaction completion.

The described bis-isothiuronium compounds can be employed in a range of photographic elements and compositions. Accordingly, one embodiment of the invention is a photographic element comprising a support, a photographic silver salt and a bis-isothiuronium compound, as described.

A silver halide developing agent is employed in the practice of the invention to provide a desired developed image. Suitable silver halide developing agents include, for example, polyhydroxybenzenes such as hydroquinone developing agents, e.g. hydroquinone, alkyl-substituted hydroquinones as exemplified by tertiary-butylhydroquinone, methylhydroquinone, 2,5-dimethylhydroquinone and 2,6-dimethylhydroquinone; catechols and'pyrogallol; halo-substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy-substituted hydroquinones such as methoxyhydroquinone or ethoxyhydroquinone; methylhydroxynaphthalene; methyl galate; aminophenol developing agents, such as 2,4-diaminophenols and methylaminophenols; ascorbic acid developing agents such as ascorbic acid, ascorbic acid ketals and ascorbic acid derivatives such as those described 'in U.S. Pat. 3,337,342 of Green issued Aug. 22, 1967; hydroxylamine developing agents such as N,N-di(2-ethoxyethy1) hydroxylamine; 3-pyrazolidone developing agents such as 1 phenyl 3 pyrazolidone and 4 methyl 4 hydroxymethyl 1 phenyl 3 pyrazolidone including those described in British Pat. 930,572 published July 3, 1963; hydroxytetronic acid, and hydroxytetronimide developing agents; reductone developing agents such as anhydro dihydro piperidino hexose reductone or anhydro dihydro pyrrolidino hexose reductone; and the like. Combinations of developing agents can be employed if desired.

The described photographic elements and photographic compositions contain a photographic salt, especially a photographic silver salt. Suitable photographic silver salt. Suitable photographic silver salts include silver chloride, silver bromide, silver bromoiodide, silver chlorobromoiodide or mixtures thereof. The photographic silver halide can be coarse or fine-grain. The emulsion containing the photographic silver halide can be prepared by any of the well-known procedures in the photographic art, such as single-jet emulsions, double-jet emulsions, such as Lippmann emulsions, ammoniacal emulsions, thiocyanate or thiether ripened emulsions, such as those described in U.S. Pat. 2,222,264 of Nietz et al. issued Nov. 14, 1940; U.S. Pat. 3,320,069 of Illingsworth issued May 15, 1967 and U.S. Pat. 3,271,157 of McBride issued Sept. 6, 1966. Surface image silver halide emulsions can be used or internal image silver halide emulsions such as those described in U.S. Pat. 2,592,250 of Davey et al. issued Apr. 8, 1952; U.S. 3,206,313 of Porter et a1. issued Sept. 14, 1965; U.S. Pat. 3,367,778 of Berriman et al. issued Feb. 6, 1968; and U.S. Pat. 3,447,927 of Bacon et al issued June 3, 1969. If desired, mixtures of surface and internal image silver halide emulsions can be used as described in U.S. Pat. 2,996,382 of Luckey et al. issued Apr. 15, 1961. Negative type emulsions can be used or direct positive silver halide emulsions such as those described in U.S. Pat. 2,184,013 of Leermakers issued Dec. 19, 1939; U.S. Pat. 2,541,472 of Kendall et al. issued Feb. 13, 1951; U.S. Pat. 3,367,778 of Berriman et al. issued Feb. 6, 1968; British Pat. 723,019; French Pat. 1,520,821; U.S. Pat. '2,- 563,785 of Ives issued Aug. 7, 1951; U.S. 'Pat. 2,456,953 of Knott et a1 issued Dec. 21,1968; and U.S. Pat. 2,861,-

885 of Land issued November 25, 1958. The silver halidev emulsion can be a regular grain emulsion such as described in Klein and Moisar, Journal of Photographic Science, V5olume 12, No. 5, September-October (1964), pages 242- 2 1.

The silver halide emulsions employed in the practice of the invention can be unwashed or washed to remove soluble salts. In the latter casethe soluble salts can be removed by chill setting and leaching or the emulsion can be coagulation washed.

The silver halide employed in the practice of the invention can be sensitized with chemical sensitizers, such as with reducing agents; silver, selenium, or tellurium compounds; gold, platinum, orpalladi um compounds; or combinations of these. Suitable procedures are described, for example, in U.S. Pat. 1,623,499 of Shepard issued Apr. 5, 1927; U.S. Pat. 2,399,083 of Waller et al. issued Apr. 23, 1946; US. Pat. 3,297,447 of McVeigh issued Jan. 10, 1967; and U.S. Pat. 3,297,446 of Dunn issued Jan. 10, 1967.

The silver halide emulsions and photographic elements and/or compositions used with this invention can contain speed increasing compounds such as polyalkylene glycols, cationic surface active agents and combinations of these as described in Piper U.S. Pat. 2,886,437; Dann et al. U.S. Pat. 3,046,134; Carrol et al. U.S. Pat. 2,944,900 and Gofie U.S. Pat. 3,294,540.

Photographic silver halide emulsions employed in the practice of the invention can be protected against the production of fog and can be stabilized against loss of sensitivity during keeping. Suitable antifoggants and stabilizers, e. g. used alone or in combination include, for example, thiazolium salts; azaindenes; mercury salts as described, for example, in U.S. Pat. 2,728,663 of Allen et al. issued Dec. 27, 1955 urazoles; sulfocatechols; oximes described, for example, in British Pat. 623,448; nitron; nitroindazoles; polyvalent metal salts described, for example, in U.S. Pat. 2,839,405 of Jones issued June 17, 1958; platinum, palladium and gold salts described, for example, in U.S. Pat. 2,566,263 of Trivelli et al. issued Aug. 28, 1951 and U.S. Pat. 2,597,915 of Yutzy et al. issued May 27, 1952.

A photographic element or composition described and used in the practice of the invention can contain various colloids alone or in combination as vehicles, binding agents and in various layers. They are transparent or translucent and include both naturally-occurring substances such as proteins, for example, gelatin, gelatin derivatives, cellulose derivatives, polysaccharides such as dextran, gum arabic and the like; and synthetic polymeric substances such as Water-soluble polyvinyl compounds like poly(vinyl pyrrolidone), acrylamide polymers and the like. Other synthetic polymeric compounds which can be employed include dispersed vinyl compounds such as in latex form and particularly those which increase dimensional stability of photographic materials. Suitable synthetic polymers include those described in U.S. Pat. 3,- 142,586 of Nottorf issued July 28, 1964; U.S. Pat. 3,193,- 386 of White issued July 6, 1955; U.S. Pat. 3,062,674 of Houck et al. issued Nov. 6, 1962; U.S. Pat. 3,220,844 of Houck et al. issued Nov. 30, 1965; U.S. Pat. 3,287,289 of Ream et al. issued Nov. 22, 1966; and U.S. Pat. 3,411,911 of Dykstra issued Nov. 19, 1968. Eifective polymers include water insoluble polymers of alkyl acrylates and methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and those which have cross-linking sites Which facilitate hardening or curing as well as those having recurring sulfobetaine units as described in Canadian Pat. 774,054.

The photographic and other layers of an element employed in the practice of the invention and described herein can be coated on a wide variety of supports. Typical supports include cellulose nitrate film, cellulose ester film, poly(vinyl acetal) film, polystyrene film, poly(ethylene terephthalate) film, ploycarbonate film and related films or resinous materials, as well as glass, paper, metal and the like. Typically a flexible support is employed, especially a paper support which can be partially acetylated or coated with baryta and/or alpha olefin polymer, particularly a polymer of an alpha olefin containing 2 to carbon atoms such as polyethylene, polypropylene, ethylene-butene copolymers and the like.

The photosensitive and/or other hardenable layers of an element used in the practice of this invention can be hardened by various organic or inorganic hardeners, alone or in combination, such as aldehydes, and blocked aldehydes, ketones, carboxylic and carbonic acid derivatives, sulfonate esters, sulfonyl halides and vinylsulfonylalkyl ethers, active halogen compounds, epoxy compounds, aziridines, active olefins, isocyanates, carbodimides, mixedfunction hardeners and polymeric hardeners such as oxidized polysaccharides like dialdehyde starch and oxyguargum and the like.

The photographic and thermosensitive elements used in the practice of the invention can contain antistatic or conducting layers. Such layers can compirse soluble salts such as chlorides, nitrates and the like, evaporated metal layers,

ionic polymers such as those described in U.S. Pat. 2,861,- 056 of Minsk issued Nov. 18, 1958 and U.S. Pat. 3,206,- 312 of Sterman et al. issued Sept. 14, 1965 or insoluble inorganic salts such as those described in U.S. Pat. 3,428,451 of Trevoy issued Feb. 18, 1969. The photographic and thermosensitive elements can also contain antihalation materials and antihalation dyes.

The photographic or other layers employed in the practice of the invention can contain plasticizers and lubricants. Suitable plasticizers and lubricants include, for example, in U.S. Pat. 2,960,404 of Milton et al. issued Nov. 1, 1966; fatty acids or esters such as those described in U.S. Pat. 2,588,765 of Robijns issued Mar. 11, 1951; U.S. Pat. 3,121,060 of Duane issued Feb. 11, 1964; and silicone resins such as those described in British 955,061.

The photographic or other layers employed in the practice of the invention can contain surfactants such as saponin; anionic compounds such as sulfonates described, for example, in U.S. Pat. 2,600,831 of Baldsiefen issued June 17, 1962; amphoteric compounds such as those described in U.S. Pat. 3,133,816 of Ben-Ezra issued May 19, 1964; and adducts of glycidol and an alkylphenol such as those described in British Pat. 1,022,878.

If desired, the photographic elements employed in the practice of the invention can contain matting agents such as starch, titanium dioxide, zinc oxide, silica, polymeric beads including beads described, for example, in. U.S. Pat. 2,922,101 of Jelley et al. issued July 11, 19 61 and U.S. Pat. 2,701,245 of Lynn issued Feb. 1, 1955.

The photographic elements employed in the practice of the invention can contain brightening agents including stilbenes, triazines, oxazoles, and coumarin brightening agents. Water-soluble brightening agents can be used such as those described in German Pat. 972,067 and U.S. Pat. 2,933,390 of McFall et al. issued Apr. 19, 1960 or dispersions of brighteners can be used such as those described in German Pat. 1,150,274; U.S. Pat. 3,406,070 of Oetiker et al. issued Oct. 15, 1968 and French Pat. 1,530,244.

The various layers including the photographic layers of an element employed in the practice of the invention can contain light-absorbing materials and filter dyes such as those described in U.S. Pat. 3,253,921 of Sawdey issued May 31, 1966; U.S. Pat. 2,274,782 of Gaspar issued Mar. 3, 1942; U.S. Pat. 2,427,583 of Silberstein et al issued Oct. 31, 1950 and U.S. Pat. 2,956,879 of Van Campen issued Oct. 18, 1960. If desired, the dyes can be mordanted, for example, as described in U.S. Pat. 3,282,699 of Jones et al. issued Nov. 1, 1966.

Spectral sensitizing dyes can be used conveniently to confer additional sensitivity to the light sensitive silver halide emulsion of the photographic elements of the invention. For instance, additional spectral sensitization can be obtained by treating the emulsion with a solution of a sensitizing dye in an organic solvent or the dye may be added in the form of a dispersion as described in Owens et al., British Pat. 1,154,781. For optimum results, the dye may either be added to the emulsion as a final step or at some earlier stage.

sensitizing dyes useful in sensitizing silver halide emulsions are described, for example, in US. Pat. 2,526,632 of Brooker et al. issued Oct. 24, 1950; US. Pat. 2,503,- 776 of Sprague issued Apr. 11, 1950; U.S. Pat. 2,492,748 of Brooker et al. issued Jan. 10, 1950 and U.S. Pat. 3,384,486 of Taber et al. issued May 21, 196-8. Spectral sensitizers which can be used include the cyanines, merocyanines, complex (trinuclear or tetranuclear) merocyanines, complex (trinuclear or tetranuclear) cyanines, holopolar cyanines, styryls, hemicyanines such as enamine, hemicyanines, oxonols and hemioxonols. Dyes of the cyanine classes can contain such basic nuclei as the thiazolines, oxazolines, pyrrolines, pyridines, oxazoles, thiazoles, selenazoles, and imidazoles. Such nuclei can contain alkyl, alkylene, hydroxyalkyl, sulfoalkyl, carboxyalkyl, aminoalkyl, and enamine groups that can be fused to carbocyclic or heterocyclic ring systems either unsubstituted or substituted with halogen, phenyl, alkyl, haloalkyl, cyano, or alkoxy groups. The dyes can be symmetrical or unsymmetrical and can contain alkyl, phenyl, enamine or heterocyclic substituents on the methine or polymethine chain.

The merocyanine dyes can contain the basic nuclei described as well as acid nuclei such as thiohydantoins, rhodanines, oxazolidenediones, thiazolidenediones, barbituric acids, thiazolineones, and malononitrile. These acid nuclei can be substituted with alkyl, alkylene, phenyl, carboxyalkyl, sulfoalikyl, hydroxyalkyl, alkoxyalkyl, alkylamino groups, or heterocyclic nuclei. Combinations of these dyes can be used, if desired. In addition supersensitizing addenda which do not absorb visible light may be included such as, for instance, ascorbic acid derivatives, azaindenes, cadmium salts, and organic sulfonic acid as described in U.S. Pat. 2,933,390 of McFall et al. issued Apr. 19, 1960 and U.S. Pat. 2,937,089 of Jones et al. issued May 17, 1960.

The sensitizing dyes and other addenda used in the practice of the invention can be added from water solutions or suitable organic solvent solutions can be used. The compounds can be added using various procedures including, for example, those described in U.S. Pat. 2,912,343 of Collins et al. issued Nov. 10, 1959; U.S. Pat. 3,342,605 of McCrossen et al. issued Sept. 19, 1967; U.S. Pat. 2,996,287 of Audran issued Aug. 15, 1961 and U.S. Pat. 3,425,835 of Johnson et al. issued Feb. 4, 1969.

The photographic layers used in the practice of this invention can be coated by various coating procedures including dip coating, airknife coating, curtain coating or extrusion coating using hoppers of the type described in Beguin U.S. Pat. 2,681,294 issued June 15, 1954. If desired, two or more layers may be coated simultaneously by the procedures described in Russell U.S. Pat. 2,761,- 791 issued Sept. 4, 1956 and Wynn British Pat. 836,095.

Thisinvention can be used with elements designed for colloid transfer processes such as described in Yackel et al. U.S. Pat. 2,716,059 issued Aug. 23, 1955; silver salt diffusion transfer processes such as described in Rott U.S. Pat. 2,352,014 issued June 20, 1944; Land U.S. Pat. 2,543,- 181 issued Feb. 27, 1951; Yackel et al. U.S. Pat. 3,020,155 issued Feb. 6, 1962 and Land U.S. Pat. 2,861,885 issued Nov. 25, 1958; color image transfer processes such as described in Rogers U.S. Pats. 3,087,817 issued Apr. 30, 1963; 3,185,567 issued May 25, 1965 and 2,983,606 issued May 9, 1961; Weyerts et al. U.S. Pat. 3,253,915 issued May 31, 1966; Whitmore et al. U.S. Pats. 3,227,550 issued Jan. 4, 1966; 3,227,561 issued Jan. 4, 1966; 3,227,- 552 issued Jan. 4, 1966 and Land U.S. Pats. 3,415,644 issued Dec. 10, 1968; 415,645 issued Dec. 10 1968; 3,415,646 issued Dec. 1 0, 1968 and imbibition transfer processes as described in Minsk U.S. Pat. 2,882,156 issued Apr. 14, 1959.

This invention can be used in elements designed for physical development such as those described in Agfa British Pat. 920,277 and Gilman et al. British Pat. 1,131,- 238.

This invention can be used with elements designed for color photography, for example, elements containing colorforming couplers such as those described in Frohlich et a1. U.S. Pat. 2,376,679 issued May 22, 1945; Jelley et al. U.S. Pat. 2,322,027 issued June 15, 1943; Fierke et al. U.S. Pat. 2,801,171 issued July 30, 1957; Godowsky U.S. Pat. 2,698,794 issued Jan. 4, 1966; Barr et al. U.S. Pat. 3,227,- 554 issued Jan. 4, 1966 and Graham et al. U.S. Pat. 3,046,- 129 issued July 24, 1962; or elements to be developed in solutions containing color-forming couplers such as those described in Mannes et al. U.S. Pat. 2,252,718 issued Aug. 19, 1941; Carroll et al. U.S. Pat. 2,592,243 issued Apr. 8, 1952 and Schwan et al. U.S. Pat. 2,950,970 issued Aug. 30, 1960 and in false-sensitized color materials such as those described in Hanson U.S. Pat. 2,763,549 issued Sept. 18, 1956.

The described bis-isothiuronium compounds are suitable in a range of physical locations in a photographic element. They can be employed in one or more layers of a photographic element, such as in a silver halide emulsion layer and/ or an overcoat layer and/ or a layer between a silver halide emulsion layer and a support. It is necessary that the described bis-isothiuronium compound be contiguous to the photographic silver compound to be stabilized or the developing agent or developing agent precursor to be activated.

Various saccharides can be employed in combination with the described bis-isothiouronium compounds. Suitable saccharides include non-reducing oligosaccharides, such as sucrose and raflinose. Other suitable saccharides are described in British Pat. 930,572 published July 3, 1963. The suitable concentration of saccharide can'vary depending upon the desired image, other components prescut, the particular bis-isothiuronium compound employed, processing conditions and the like. A concentration of about 0.01 to about 20 moles of saccharide per mole of described bis-isothiuronium compound is usually suitable.

The described bis-isothiuronium compounds can be employed in a range of photographic compositions. Accordingly, another embodiment of the invention is a photographic composition comprising photographic silver salt and a bis-isothiouronium compound, as described, having an intermediate ureylene or ether moiety between the iso thiuronium moieties. The photographic composition istypically a photographic silver halide emulsion.

Also, the described bis-isothiuronium compounds can be employed in photographic silver salt processing compositions, such as in silver halide developers, stabilizing compositions, fixing compositions, hardeners, and the like. Accordingly, another embodiment of the invention is a photographic silver salt processing composition comprising a silver hafide developing agent, as described, and a bis-isothiuronium compound, also as described.

The photographic composition can contain a silver halide developing agent, as described. The concentration of silver halide developing agent suitable is about 0.25 mole to about 4 moles of developing agent per mole of photographic silver compound in the photographic composition.

After exposure, a latent image in a photographic ele ment comprising a support, photographic silver halide, a silver halide developing agent, and a bis-isothiuronium compound, as described, can be developed merely by heating the element, e.g. to about C. to about 250 C., until a desired image is developed.

A temperature range of about 90 C. to about 250 C. is suitable. By increasing or decreasing the time of heating, a higher or lower temperature within the described range can be employed. A developed and stable image usually results within about 1 second to about 60* seconds.

Processing is usually carried out under ambient conditions of pressure and humidity. Pressures and humidity outside normal atmospheric conditions can be employed, if desired, however, normal atmospheric conditions are preferred. 7

Various means can be employed in providing the necessary heating. The described element can be brought into contact with a simple hot plate, iron, rollers or the like.

Small concentrations of moisture can be present during processing, such as the concentrations present in conventional photographic paper supports at atmospheric conditions, such as at about 25 C. and 40%relative humidity.

While it is not necessary, anactivator, such as an or' ganic activator precursor, can be employed with the described bis-isothiuronium compounds. Activator as em ployed herein is intended to refer to an agent Which helps cause the developing agent, at processing temperature, employed with the described bis-isothiuronium compounds, to develop a latent image in a photographic silver salt contiguous to the developing agent. An organic activator precursor can be employed, as described in Belgian Pat. 709,967 published Feb. 29, 1968. Examples of classes of activator precursors include guanidinium salts, such as guanidinium trichloroacetate, diguanidinium glutarate, succinate, malonate, and the like; quarternary ammonium malonates, such as piperazinium or piperidinium malonate; amino acids, such as 6-aminocaproic acid, glycine; and the like. Other activator precursors are described, for example, in British Pat. 998,949.

The concentration of described bis-isothiuronium compound which is suitable can vary depending upon the desired image, processing conditions, particular bis-isothiuronium compound, and the like. A concentration of bis-isothiuronium compound, as described, in a photographic element or composition, also as described, is usually about 1 to about 6 moles of bis-isothiuronium compound per mole of photographic silver salt present.

The following examples are included for a further understanding of the invention.

EXAMPLE 1 75.0 g. (0.4 mole) of 1,2-bis(2-chloroethoxy)ethane is admixed with 60.8 g. (0.8 mole) of thiourea in 1.5 liters of isopropanol. The resulting mixture is heated to reflux temperature and refluxed for. 24 hours forming the desired 1,8 (3,6-dioxaoctane)bis(isothiuronium chloride) represented by the formula:

N 1 NH:

EXAMPLE 2 57.3 g. (0.4 mole) of bis(2 chloroethyl)ether is admixed with 60.8 g. (0.8 mole) of thiourea in 1.5 liters of isopropanol. The resulting mixture is heated to reflux temperature and refluxed for 24 hours forming the desired 1,5 (3 oxapentane)bis(isothiuronium chloride) represented by the formula:

N 2 NH:

The resulting compound can be in hydrate form. A purified product is recovered by reducing the volume of the reaction product to about 300 ml. by boiling, dissolving the resulting product in boiling methanol, adding isopropanol to provide a total volume of about 500 ml. and then boiling the mixture until a volume of about 300 ml. is reached. The resulting solid precipitate is'filtered. The purified product has a melting point of 129 C. and ele- "mental analysis based on the dihydrate form of the compound provides the following results:

Theoretical (percent): C, 24.6; H, 4.8; N, 16.7. Found (percent): C, 21.5; H, 5.4; N. 16.9.

EXAMPLE 3 224 g. (1.31 mole) of bis(3-chloropropyl)ether is admixed with 250 g. (3.28 mole) of triourea in 3 liters of isopropanol. The reaction mixture is heated to reflux temperature and refluxed for 48 hours to form the desired 1,7 (4 oxaheptane)-bis(isothiuronium chloride) represented by the formula:

The crude product is purified by removing most of the isopropanol by boiling the reaction mixture after refluxing. Then 4 liters of acetone is added and the desired product is permitted to precipitate from the solution. The product is recrystallized from the isopropanol and filtered. It has a melting point of C.

EXAMPLE 4 79.9 g. (0.4 mole) of bis(4-chlorobutyl)ether is admixed with 60.8 g. (0.8 mole) of thiourea in 1.5 liters of isopropanol. The reaction mixture is heated to reflux temperature and refluxed for 24 hours. The desired 1,9-(5- oxanonane)bis(isothiuronum chloride) represented by the formula:

NHz -NH2 is produced. The crude product is recovered.

EXAMPLE 5 102 g. (0.888 mole) of bis(chloromethyl)ether is admixed with 134 g. (1.77 mole) of thiourea in 3 liters of isopropanol. The reaction mixture is heated to reflux temperature and refluxed for 24 hours. The desired product, 1,3 (2-oxapropane)-bis(isothiuronium chloride) is produced represented by the formula:

N /NH2 H \CSCH2O ornso 201- It is recovered having a MP. of 176 C.

The preparation of related compounds is described, as carried out in ethanol, in Journal of Organic Chemistry, vol. 34, No. 4 (1969), page 1143.

EXAMPLE 6 EXAMPLE 7 29.5 g. (0.133 mole) of silver trifluoroacetate is dissolved in one liter of methanol. 24.0 g. (0.067 mole) of 1,8 (3,6-dioxaoctane(bis)isothiuronium chloride) monohydrate is added to the resulting solution. An exothermic reaction occurs. The resulting solid precipitate as separated by filtration. The filtrate is concentrated by warming the filtrate in a vacuum. The resulting solid product is recrystallized -from acetone. The desired 1,8-(3,6-dioxaoctane)bis(isothiuronium trifluoroacetate) has a melting point of 82 C.

EXAMPLE 8 1,8-(3,6-dioxaoctane)bis(isothiuronium formate), having a melting point of 122 C., is prepared by reacting potassium formate with 1,8 (3,6 dioxaoctane(bis)isothiuronium chloride) monohydrate in methanol employing the procedure of Example 6.

EXAMPLE 9 g 17.0 g. (0.1 mole of silver nitrate is dissolved in 900 ml. of methanol, 17.8 g. .(0.05 mole) of 1,8-(3,6-dioxaoctane)-bis(isothiuronium chloride) monohydrate is admixed with the resulting solution. An exothermic reaction occurs. A crude product in the form of an oil is produced.

EXAMPLE p 687 g. (2.46 mole) of .silver p-toluene sulfonate is dissolved in 7 liters of water. 440 g. (1.23 mole) of 1,8-(3,6- dioxaoctane)bis(isothiuronium chloride) monohydrate in 1 liter of water is admixed with the resulting solution with stirring at room temperature, i.e., about 20 C. Silver chloride is precipitated and separated from the solution by filtration. The filtrate is evaporated at room temperature, i.e., about 20 C., by permitting the filtrate to stand in open air at atmospheric pressure. The resulting solid crystals from the filtrate are recrystallized'from acetone to produce the desired pure 1,8-(3,6-dioxaoctane)bis(isothiuronium p-toluenesulfonate). This is identified by elemental analysis. It is in hydrate form.

EXAMPLE l 1 1,8-(3,6-dioxaoctane)bis(isothiuronium chloroacetate), having a melting point of 144 C., is prepared by reacting sodium chloroacetate with 1,8 (3,6-dioxactane)bis(isothiuronium chloride) monohydrate in methanol employing the procedure of Example 6.

EXAMPLE 12 1,8 (3,6 dioxaoctane)bis(isothiuronium dichloroacetate), having a melting point of 140 C., is prepared by reacting sodium dichloroacetate with 1,8 (3,6 dioxaoctane)bis (isothiuronium chloride) monohydrate employing the procedure of Example 6.

EXAMPLE 13 1,7-(4-oxaheptane)bis(isothiuronium trifluoroacetate) is prepared by reacting 1,7 (4-oxaheptane)bis(isothiuronium chloride) with silver trifluoroacetate employing the procedure described in Example 7.

EXAMPLE 14 1,7 (4-oxaheptane)bis(isothiuronium p-toluenesulfomate) is prepared by reacting silver p-toluenesulfonate with 1,7-(4-oxaheptane)bis(isothiuronium chloride) employing the procedure described in Example 10.

EXAMPLE 15 100 ml. of a 12% by weight aqueous solution of pigskin gelatin, maintained at 41 C., is mixed with the following components:

(a)v 1,12 bis(isothiuronium)-4,9-dioxo-3,5,8,IO-tetraazadodecane dichloride g 3 ,(b) 4 hydroxymethyl 4 methyl-l-phenyl-3-pyrazolidone (2 g. in ml. of methanol) ml 20 (c) Sucrose 8 g (d) Fine grain silver chloride gelatino emulsion ml 10 ,(e) Saponin (2% by weight aqueous solution) ml 3 EXAMPLE. 16

The procedure set out in Example 15 is repeated with the exceptions that 4 grams of 1,7-(4-oxaheptane)bis(isothiuronium chloride) is employed in place of the described 3 g. of 1,12bis(isothiuronium)-4,9-dioxo-3,5,8,10-tetraazadodecane dichloride and the coating on the paper support contains .39.9 mg. of silver and 584 mg. of gelatin per 929 square centimeters of support. Upon sensitometric exposure and heating, as described in Example 14, a dark brown-black image is produced having a yellowishback= ground. The developed image has a reflection maximum density of 1.45, a reflection minimum density of 0.18 and a gamma of 1.20. I

The developed image is held in room light for 2 days and no significant decrease in maximum density or increase in minimum density is observed.-

EXAMPLE 17 This demonstratesthatsucrosein a photographic element'as described can provide increased maximum densityand gamma without an increase in minimum density of a'developed image.

A photographic element A is prepared by mixing the following components and coating the resulting composition on a paper support:

Pigskin gelatin (12% by weight aqueous solution at 41 C.) rnl 50 1,7 (4 oxaheptane)bis(isothiuronium chloride) dihydrate g. 1.8 Sucrose g 4.0 4-hydroxymethyl- 4 methyl 1 phenyl 3 pyrazolidone .-.g 1.0 Saponin (4% by weight aqueous solution) -...L m1 1.0 Fine grain silver chloride gelatino emulsion ml 5 .0

exposed and heated in the same manner as photographic.

element A but without sucrose, with a silver coverage of 29.7 mg. of silver per 929 square centimeters of. support and gelatin coverage of 440 mg. per 929 square centimeters of supports, provides a developed image having a maximum density of 0.46, a mini-mum density of 0.10 and a gamma of 0.38. EXAMPLE 18 Similar results are provided as in Example 17 employing mannitol in place of sucrose.

EXAMPLE 19 Similar results are provided as in Example 17 employing sorbitol in place of sucrose.

I EXAMPLE 20 i The following components are mixed:

Pigskin gelatin (12% by weight aqueous solution) ml 50.0 1,8 (3,6 dioxaoctane)bis(isothiuronium trifluoroacetate). g 2.5 Hydroquinone g 1.0 4-methyl-1-phenyl-3-pyrazolidone g 0.5 Saponin (4% by weight aqueous solution) ml 3.0 Fine grain silver chloride gelatino emulsion ml 5.0

The resulting photographic composition is coated on a paper support having a gelatin coating of 290 mg. of gelatin per 929 square centimeters of support. The photographic composition is coated at 29.5 mg. of silver and 238 mg. of gelatin per 929 square centimeters of support. The photographic element is sensitometrically exposed and then heated by contacting the side opposite the photographic coating on a hot metal block at 200 C. for five seconds. A developed image is produced having a maximum reflection density of 1.38, a minimum reflection density of 0.15 and a gamma of 1.10.

13 EXAMPLE 21 A photographic composition is prepared by mixing the following components: Pigskin gelatin (12% by weight aqueous solu- The photographic composition is coated on a poly(ethylene terephthalate) film support at a silver coverage of 41.0 mg. of silver per 929 square centimeters of support and 606 mg. of gelatin per 929 square centimeters of support. The resulting photographic film is sensitometrically exposed and then heated by contacting the side of the film opposite the photographic coating with a hot metal block at 160 C. for 15 seconds. A stable, purple-black image is developed having a maximum density of 1.14, a minimum transmission density of 0.08, and a gamma of 1.02.

EXAMPLE 22 A photographic composition is prepared by mixing the following components: Poly(viny1 alcohol) (10% by weight aqueous solution) ml Surfactant 10% by weight aqueous solution of Surfactant 10G which is an adduct of glycidol with alkylphenol sold by Alcolac Chemical Corp., Baltimore, Md., U.S.A.) "ml..- 1.0 1,8 (3,6 dioxaoctane)bis(isothiuronium trifluoroacetate) g 2.5 Hydroquinone g 1.0 S-methyl-1-phenyl-3-pyrazolidone g 0.8 Fine grain silver chloride gelatino emulsion ml 5.0

The photographic composition is coated on a paper support at a silver coverage of 42.5 mg. of silver per 929 square centimeters of support.

The resulting photographic element is sensitometrically exposed and then heated by contacting the side of the photographic element opposite the photographic composition with a hot metal block at 200 C. for 10 seconds. A stable, brown image is developed having a maximum reflection density of 0.82, a minimum reflection density of 0.24 and a gamma of 0.62.

EXAMPLE 23 A bis-chloride compound within Formula II, as described, wherein a is 2, is prepared by reacting two moles of chloroethylisocyanate with 1 mole of ethylene diamine in 500 ml. of chloroform at reflux temperature. The resulting solid product is recovered by filtration.

One mole of the purified product represented by the formula ClCHzCHzNH NHCHzCHzNHNI-ICHzCHzCI is mixed with two moles of thiourea in 500 ml. of ethanol. The resulting reactant mixture is heated to reflux temperature, e.g., about 80 C., until reaction completion. The mixture is cooled and the resulting solid product recovered by filtration. The product 1,12-bis(isothiuronium) 4,9 dioxo 3,5,8,10 tetraazadodecane dichloride is represented by the formula:

NHz NH The product is identified by elemental analysis.

Isothiuronium compounds such as those described elsewhere herein can also be employed in light-sensitive diazotype compositions. Two-component, light-sensitive diazotype compositions generally include at least one lightsensitive diazonium salt and at least one coupler compound which can react with the diazonium salt, typically in an alkaline medium, to form an azo dye. In addition, there can be present various other additives such as ultraviolet absorbers, acid stabilizers (to prevent premature coupling of the diazonium salt and the coupler), as well as additional known addenda. Use of a diazotype element generally involves an imagewise exposure to activating radiation e.g., light including actinic light, through an original, whereupon impinging light decomposes the diazonium salt. Thereafter, development of the exposed diazotype layer is conveniently accomplished by treatment with an alkaline medium such as aqueous ammonia vapor. During development, the coupler component reacts (couples) with undecomposed diazonium salt to form an azo dye in unexposed areas and thereby provide a positive photographic image corresponding to that of the original.

However, in lieu of conventional processing by an externally supplied alkaline medium, certain materials, such as the present isothiuronium compounds, can be incorporated into the diazotype composition as an alkaline releasing development precursor. The isothiuronium compounds described herein, when heated, such as up to approximately C., generate an alkaline material suitable for initiating the coupling reaction. As such, simple heating produces desirable image development without requiring an outside source of ammonia or another alkaline material. The development procedure is thus simplified accordingly. The following example illustrates use of the isothiuronium compounds of the invention as thermally activated alkaline releasing development precursors for diazotype media. A coating solution including:

Water soluble cellulose acetate 10% by weight aqueous solution) ml 25.00 Cyclohexylsulfamic acid g 0.5 p-Diazodiethylaniline zinc chloride g 0.25 6,7 dihydroxy 2 naphthalene sodium sulfonate g 0.5 Surfactant 10% by Weight aqueous solution) ml 1.0 1,8 (3,6 dioxaoctane)bis(isothiuronium trifluoroacetate) g 1.0

is doctor blade coated on a polyester film base at 0.004- inch Wet thickness. After drying, the resultant photographic element is exposed to a UV source through a high contrast image pattern until the diazonium salt is decomposed in the light struck areas. The exposed element is then heated to 160 C., for one minute. A medium purple-brown dye image is formed in previously unexposed regions. In the absence of the 1,8-(3,6-dioxaoctane) bis(i sothiuronium trifluoroacetate), no dye image is formed.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

What is claimed is:

1. A photographic element comprising a photographic silver salt and a bis-isothiuronium compound wherein said bis-isothiuronium compound is represented by the forwherein R R and R are each alkylene containing one to five carbon atoms; Y is sulfur, oxygen or n is O, 1 or 2; when n is and Y is oxygen or sulfur, R plus R contain at least two carbon atoms; X is an anion; m is l or 2.

2. A photographic element as in claim 1 wherein said bis-isothiuronium compound is l,l2-bis(isothiuronium)- ethyl)urea bis(p-toluenesulfonate).

3. A photographic element as in claim 1 wherein said bis-isothiuronium compound is l,l2-bis(isothiuronium)- 4,9-dioxo-3,5,8,IO-tetraazadodecane dichloride.

4. A photographic element as in claim 1 wherein said bis-isothiuronium compound is 1,7(4-oxaheptane)bis(isothiuronium chloride).

5. A photographic element as in claim 1 wherein said bis-isothiuronium compound is 1,8(3,6-dioxaoctane)bis (isothiuronium trifluoroacetate).

6. A photographic element as in claim 1 wherein said bis-isothiuronium compound is present as a formate, nitrate, p-toluenesulfonate, chloride, bromide, trifluoroacetate, chloroacetate, ethyl sulfate or dichloroacetate salt.

7. A photographic element as in claim 1 comprising a silver halide development agent.

8. A photographic element as in claim 1 comprising sucrose.

9. A photographic silver salt processing composition comprising a silver halide developing agent and a bisisothiuronium compound wherein said bis-isothiuronium compound is represented by the formula:

n is 0, 1 or 2; when n is O and Yis oxygenor sulfur, R plus R contain at least two carbon atoms; X is an anion;-

10. A photographic composition as in claim 9 wherein said bis-isothiuronium compound is l,3-bis(2-is othiuro-,

niumethyl)urea bis (p-toluene sulfonate) 11. A photographic composition as in claim 9 wherein said bis-isothiuronium compound is l,12-bis(isot hiuro-" nium)-4,9-dioxo-3,5,8,l0-tetraazadodecane dichloride.

12. A photographic composition as in claim 9 wherein said bis-iso thiuronium compound is l,7-(4 oxaheptane f bis(isothiu'ronium chloride) dihydrate. I

13. A photographic composition asin claim 9 wherein said bis-isothiuronium compound is 'l,8-(3,6-dioxaoctane)' bis(isothiuronium trifluoroacetate).

14. A photographiccomposition as in claim 9 com 

